This invention relates to a load balancer capable of transferring articles easily, and more particularly to a load balancer adapted to set the load of articles to substantially zero by utilizing an air pressure.
A known load balancer of this kind is disclosed in, for example, Japanese utility model application Kokai publication No. 61-197079. In this conventional example, an air brake cylinder provided in series with respect to a balance cylinder is operated to control a piston rod of the balance cylinder unitarily with the balance cylinder, and the load of articles, which is transmitted from an article support arm, is transmitted to a weight sensing cylinder provided in series just as the balance cylinder, to generate a reference pressure corresponding to the load. The compressed air the pressure of which corresponds to the reference pressure is supplied to a chamber in the balance cylinder. When the air brake is then released, this compressed air causes a reaction force corresponding to the load to be generated, which is applied to the support arm via the piston and piston rod of the balance cylinder to set the load of the articles held on the support arm to substantially zero. This enables the articles to be treated and transferred easily by human power.
However, in order to make the air brake, which is provided in series with respect to the balance cylinder, fix the piston rod of the balance cylinder when the load of the articles is transmitted to the weight sensing cylinder to set a reference pressure, the necessity of setting the axial length of the air brake considerably large occurs. Therefore, the axial length of a balance unit consisting of the weight sensing cylinder, balance cylinder and air brake is necessarily set large. Accordingly, the height of the load balancer necessarily becomes large, so that it becomes unsuitable to use the load balancer, for example, inside a building or under a construction machine and an aircraft.